Abstract: In order to make a sound, one end of the straw is sealed with blowing another end of the straw. Based on the software of spectral analysis, fundamental frequency of the acoustic signal is ascertained. The differ- ence between theory and experiment is pointed out. In theory, since the corresponding tube length of fundamental frequency is a quarter of the acoustic wavelength, the sound velocity can be calculated with fundamental frequency and tube length. But in fact, the effective tube length is the combination of the real tube length and the end correc- tion which is changed by the different thickness and shape of the tube. In experiment, for the straws with the diame- ter of 1.1cm and 0.6cm, better sound velocity is achieved with the application of the end correction of 0.5d and l d respectively. Besides, if the tube length is too short, it will be hard to acquire the accurate fundamental frequency.

Key words: sound velocity, resonant pipe, spectrum analysis